DANTE

Official description (from the manual):
This trash-talking, cool-as-ice demon slayer attacks using both his longsword and his trusty revolvers. Possessing both street smarts and the strength of even the strongest demons, Dante can jump long distances, perform acrobatic double jumps and bound off walls to get where he needs to.

Non-official description:
Many years after the incident at Mallet Island, Dante still runs his demon hunting shop 'Devil Never Cry'. He recieves a request by a member of the Vie de Marli clan to aid them against an evil human who wishes to use an old ritual to gain the power of devils. Using his sword, Rebellion, Dante heads in.

LUCIA

Official description (from the manual):
Lithe, quick and agile, this mysterious, sexy demon fighter will prove that she is a formidable foe. Her first weapons of choice are two ornately crafted curved daggers for attacks of the up-close and personal nature. She moves like a cat and uses throwing knives for long-range attacks. When cornered, Lucia will execute her stunning triple wall jump.

Non-official description:
A member of the Vie de Marli clan of guardians that have the blood of demons. She, as instructed by Matier, will go on her own quest to prevent Arius from acheiving his dark goals. She is also the one who hired Dante for the same mission.

MATIER

Non-official description:
An old member of the Vie de Marli guardians. She seems to possess vast knowledge of many facets of Sparda and promises Dante that she would tell him his stories after the entire ordeal.

ARIUS

Non-official description:
The evil man who wishes to gain the power of a great demon. He is the head of an international corporation and has heard of the rituals used by the clans in the area to gain the power of devils. He wishes to use these rituals to rule the world.

Credits:

Thanks to Trickshot for writing the non-official descriptions.